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Last updated on July 15th, 2025

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Derivative of e^-t

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We use the derivative of e^-t, which is -e^-t, as a measuring tool for how the exponential decay function changes in response to a slight change in t. Derivatives help us calculate decay rates in real-life situations. We will now talk about the derivative of e^-t in detail.

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What is the Derivative of e^-t?

We now understand the derivative of e^-t. It is commonly represented as d/dt (e^-t) or (e^-t)', and its value is -e^-t. The function e^-t has a clearly defined derivative, indicating it is differentiable over the real numbers. The key concepts are mentioned below: Exponential Function: e^-t represents an exponential decay function. Chain Rule: A rule for differentiating composite functions like e^-t. Negative Sign: The negative exponent indicates that the function decreases as t increases.

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Derivative of e^-t Formula

The derivative of e^-t can be denoted as d/dt (e^-t) or (e^-t)'. The formula we use to differentiate e^-t is: d/dt (e^-t) = -e^-t The formula applies to all t in the real number set.

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Proofs of the Derivative of e^-t

We can derive the derivative of e^-t using proofs. To show this, we will use the rules of differentiation. There are several methods we use to prove this, such as: By First Principle Using Chain Rule We will now demonstrate that the differentiation of e^-t results in -e^-t using the above-mentioned methods: By First Principle The derivative of e^-t can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient. To find the derivative of e^-t using the first principle, we will consider f(t) = e^-t. Its derivative can be expressed as the following limit. f'(t) = limₕ→₀ [f(t + h) - f(t)] / h … (1) Given that f(t) = e^-t, we write f(t + h) = e^-(t + h). Substituting these into equation (1), f'(t) = limₕ→₀ [e^-(t + h) - e^-t] / h = limₕ→₀ [e^-t (e^-h - 1)] / h = e^-t limₕ→₀ [(e^-h - 1) / h] Using limit properties, the limit simplifies to -1. f'(t) = -e^-t. Hence, proved. Using Chain Rule To prove the differentiation of e^-t using the chain rule, We use the formula: u = -t so that e^-t = e^u By the chain rule, the derivative of e^u with respect to t is (de^u/du) * (du/dt). We know that de^u/du = e^u and du/dt = -1. Substituting, we find: d/dt (e^-t) = e^(-t) * (-1) = -e^-t

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Higher-Order Derivatives of e^-t

When a function is differentiated several times, the derivatives obtained are referred to as higher-order derivatives. Higher-order derivatives can be a little tricky. To understand them better, think of a car where the speed changes (first derivative) and the rate at which the speed changes (second derivative) also changes. Higher-order derivatives make it easier to understand functions like e^-t. For the first derivative of a function, we write f′(t), which indicates how the function changes or its slope at a certain point. The second derivative is derived from the first derivative, which is denoted using f′′(t). Similarly, the third derivative, f′′′(t), is the result of the second derivative, and this pattern continues. For the nth derivative of e^-t, we generally use fⁿ(t) for the nth derivative of a function f(t), which tells us the change in the rate of change (continuing for higher-order derivatives). Each derivative of e^-t is (−1)ⁿ e^-t.

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Special Cases:

When t approaches infinity, the function e^-t approaches zero, meaning the derivative -e^-t also approaches zero. When t is 0, the derivative of e^-t = -e^0, which is -1.

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Common Mistakes and How to Avoid Them in Derivatives of e^-t

Students frequently make mistakes when differentiating e^-t. These mistakes can be resolved by understanding the proper solutions. Here are a few common mistakes and ways to solve them:

Mistake 1

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Not applying the chain rule correctly

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Students may forget to apply the chain rule, which can lead to incorrect results. They might forget the negative sign from the derivative of the exponent -t. Ensure that each step is written in order, and remember that the derivative of -t with respect to t is -1.

Mistake 2

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Misunderstanding the negative exponent

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Students might not correctly interpret the negative exponent and its impact on the derivative. Keep in mind that the negative exponent implies a decreasing exponential function, and thus its derivative is negative.

Mistake 3

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Incorrectly simplifying the expression

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While differentiating functions like e^-t, students might incorrectly simplify the expression. Ensure that the negative sign is included in the final derivative expression. For example, the correct derivative is -e^-t, not e^-t.

Mistake 4

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Forgetting the base of the exponential

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A common mistake is forgetting that e is the base of the natural logarithm, leading to incorrect differentiation. For example, d/dt (e^-t) = -e^-t, not -te^-t.

Mistake 5

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Ignoring the constant rule

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When differentiating terms like 5e^-t, students may forget to multiply the constant. For example, they might incorrectly write d/dt (5e^-t) = 5e^-t. The correct expression is d/dt (5e^-t) = -5e^-t.

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Examples Using the Derivative of e^-t

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Problem 1

Calculate the derivative of (e^-t * e^-2t)

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Here, we have f(t) = e^-t * e^-2t. Using the product rule, f'(t) = u′v + uv′ In the given equation, u = e^-t and v = e^-2t. Let’s differentiate each term, u′ = d/dt (e^-t) = -e^-t v′ = d/dt (e^-2t) = -2e^-2t Substituting into the given equation, f'(t) = (-e^-t)(e^-2t) + (e^-t)(-2e^-2t) = -e^-3t - 2e^-3t Simplifying, we get, f'(t) = -3e^-3t Thus, the derivative of the specified function is -3e^-3t.

Explanation

We find the derivative of the given function by dividing the function into two parts. The first step is finding its derivative and then combining them using the product rule to get the final result.

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Problem 2

The temperature of a cooling object can be modeled by T(t) = e^-t, where T is the temperature and t is time in minutes. If t = 5 minutes, find the rate of change of temperature.

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We have T(t) = e^-t (temperature model)...(1) Now, we will differentiate the equation (1) Take the derivative of e^-t: dT/dt = -e^-t Given t = 5 (substitute this into the derivative) dT/dt = -e^-5 Therefore, the rate of change of temperature at t = 5 minutes is -e^-5.

Explanation

We find the rate of change of temperature at t = 5 minutes, which means that at a given point, the temperature decreases exponentially as time increases.

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Problem 3

Derive the second derivative of the function y = e^-t.

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The first step is to find the first derivative, dy/dt = -e^-t...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dt² = d/dt [-e^-t] = -(-e^-t) = e^-t Therefore, the second derivative of the function y = e^-t is e^-t.

Explanation

We use the step-by-step process, where we start with the first derivative. By differentiating again, we find the second derivative, simplifying the terms to find the final answer.

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Problem 4

Prove: d/dt (e^-2t) = -2e^-2t.

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Let’s use the chain rule: Consider y = e^-2t To differentiate, we use the chain rule: dy/dt = (d/dt [e^u]) * (du/dt) where u = -2t We know that d/dt [e^u] = e^u and du/dt = -2 Substituting, we find: dy/dt = e^-2t * (-2) = -2e^-2t Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. We replaced the exponent with its derivative to derive the equation.

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Problem 5

Solve: d/dt (e^-t/t)

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To differentiate the function, we use the quotient rule: d/dt (e^-t/t) = (d/dt (e^-t) * t - e^-t * d/dt(t)) / t² We substitute d/dt (e^-t) = -e^-t and d/dt (t) = 1 = (t * -e^-t - e^-t * 1) / t² = (-te^-t - e^-t) / t² Therefore, d/dt (e^-t/t) = -(t + 1)e^-t / t²

Explanation

In this process, we differentiate the given function using the quotient rule. As a final step, we simplify the equation to obtain the final result.

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FAQs on the Derivative of e^-t

1.Find the derivative of e^-t.

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2.Can we use the derivative of e^-t in real life?

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3.Is it possible to take the derivative of e^-t at any point?

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4.What rule is used to differentiate e^-t/t?

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5.Are the derivatives of e^-t and e^t the same?

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6.Can we find the derivative of e^-t formula using first principles?

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Important Glossaries for the Derivative of e^-t

Derivative: The derivative of a function indicates how the given function changes in response to a slight change in t. Exponential Function: A function of the form e^x, where e is the base of the natural logarithm, representing exponential growth or decay. Chain Rule: A rule for differentiating composite functions. Quotient Rule: A method for finding the derivative of a quotient of two functions. Exponential Decay: A process where quantities decrease at a rate proportional to their current value, often modeled by functions like e^-t.

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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